Programmable mechanical metamaterials: the role of geometry

Area of Science:

• Materials Science
• Mechanics of Materials
• Metamaterials

Background:

• Biholar metamaterials are quasi-2D rubber slabs with two alternating hole sizes.
• Previous work demonstrated programmable mechanical response to uniaxial compression via lateral confinement.
• Non-monotonic or hysteretic compression resistance was observed within specific strain ranges.

Purpose of the Study:

• To investigate the influence of geometric parameters on the mechanics of biholar metamaterials.
• To explore how wall thickness (t) and hole size ratio (χ) tune programmability.
• To understand the transition from biholar to monoholar behavior.

Main Methods:

• Experimental and numerical studies of biholar metamaterial mechanics.
• Systematic variation of dimensionless geometric parameters t and χ.
• Analysis of compression resistance under varying lateral confinement.

Main Results:

• Geometric parameters t and χ significantly tune the ranges of tunable mechanical response.
• Extreme values of t and χ reveal new physical behaviors.
• A crossover from biholar to monoholar behavior occurs at low χ, linked to elastic instabilities.

Conclusions:

• Moderate values of wall thickness (t) and size ratio (χ) yield the widest programmability.
• The study provides guidelines for designing programmable biholar metamaterials.
• Understanding geometric effects is crucial for tailoring metamaterial applications.